Synthesize several retinoids with better pharmacological properties than those that have already been tested. The approach will involve the synthesis of several different retinoids, the choice of which will be dictated by the needs and interes. In general, the contractor will: synthesize, purify, and characterize a variety of retinoids; conduct a systematic structure-activity relationship; synthesize analogs of vitamin A with both steric and electronic modifications in the ring, the side chain, and the polar terminals; prepare retinoids with potential organ specificity; correlate the activity of several substituted phenyl retinoids with the a values of three substituents; and supply the synthetic retinoids in the purest possible form to NCI for in vitro biological evaluations. Data documenting the chemical purity of each compound and a small sample of the compound will be submitted to the NCI on which determinations of purity can be made.